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Publication numberUS4300878 A
Publication typeGrant
Application numberUS 06/181,588
Publication dateNov 17, 1981
Filing dateAug 27, 1980
Priority dateAug 27, 1980
Also published asDE3173193D1, EP0046688A2, EP0046688A3, EP0046688B1
Publication number06181588, 181588, US 4300878 A, US 4300878A, US-A-4300878, US4300878 A, US4300878A
InventorsDonald G. Ible
Original AssigneeThe Firestone Tire & Rubber Company
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Extrusion die for forming composite rubber-cord strip
US 4300878 A
Abstract
A die structure for forming a composite rubber-cord strip is provided having a die throat whose aperture width at entry is greater than at exit, while its height at entry is smaller than at exit, thus providing a substantially constant cross-sectional area of the throat throughout; rubber is supplied to the entry along a path parallel to the cords, and from a cord guide whose hole spacing is greater than the cord spacing in the ply at the die exit.
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Claims(8)
What is claimed is:
1. In an extrusion die-throat having a composite-forming aperture with an entry for advancing parallel cords and elastomer and an exit for the composite, the improvement comprising
a first pair of opposed aperture sidewalls converging from entry to exit; and
a second pair of opposed upper and lower aperture walls diverging from entry to exit;
said pairs of walls forming cross-sectional areas which remain substantially constant, and whose major dimensions remain in the same plane, from entry to exit.
2. In an extrusion die-throat having a composite-forming aperture with an entry for advancing parallel cords and elastomer and an exit for the composite, the improvement comprising
a first pair of opposed aperture sidewalls converging from entry to exit;
a second pair of opposed upper and lower aperture walls diverging from entry to exit;
laterally spaced ramp-pairs adjacent the entry; and converging channels recessed between the ramps of each said pair.
3. In an extrusion die-structure having a die-throat with a composite-forming aperture having an entry for advancing parallel cords and elastomer and an exit for the composite, the improvement comprising
a first pair of opposed aperture sidewalls converging from entry to exit;
a second pair of opposed upper and lower aperture walls diverging from entry to exit;
laterally spaced ramp-pairs converning upon the entry;
a cord guide engaging said ramp-pairs; and
a recess between the ramps of each said pair and forming with a respective side of said guide a channel for advancing elastomer.
4. In an extrusion die-throat having a composite-forming aperture with an entry for advancing parallel cords and elastomer and an exit for the composite, the improvement comprising
a first pair of opposed aperture sidewalls converging from entry to exit;
a second pair of opposed upper and lower aperture walls diverging from entry to exit;
laterally spaced ramp-pairs converging upon the entry; and
recesses between said ramp pairs forming converging channels for advancing elastomer;
the cross-sectional area of the aperture remaining substantially constant from entry to exit.
5. In an extrusion die structure having a die-throat with a composite-forming aperture having an entry for advanging parallel cords and elastomer and an exit for the composite, the improvement comprising
a first pair of opposed aperture sidewalls converging from entry to exit;
a second pair of opposed upper and lower aperture walls diverging from entry to exit;
two laterally spaced ramp-pairs converging upon the entry;
a cord guide engaging said ramp-pairs; and
recesses between the ramps of each said pair forming with a respective side of said guide a pair of converging channels for advancing elastomer;
the cross-sectional area of the aperture remaining substantially constant throughout.
6. In an extrusion die-throat having a composite-forming aperture with an entry for advancing parallel cords and elastomer and an exit for the composite, the improvement comprising
a first pair of opposed aperture sidewalls converging from entry to exit; and
a second pair of opposed upper and lower aperture walls diverging from entry to exit;
said pairs of walls forming rectangular parallelogram cross sections whose major dimensions remain in the same plane from entry to exit.
7. In an extrusion die-throat having a composite-forming aperture with an entry for advancing parallel cords and elastomer and an exit for the composite, the improvement comprising
a first pair of opposed aperture sidewalls converging from entry to exit; and
a second pair of opposed upper and lower aperture walls diverging from entry to exit;
said pairs of walls forming transversely elongated cross sections whose major dimensions remain in the same plane from entry to exit.
8. An extension die-throat as in claim 1 6 or 7 and converging channels communicating with the entry and extending substantially parallel to the advancing cords.
Description
FIELD OF THE INVENTION

In the production of cord-reinforced elastomer strips for the construction of vehicle tires, it is common practice to pass cords, such as wire-cords, in parallelism through a guide and thereupon to extrude rubber around the wires.

Uniformity of rubberization and the maintenance of accurate cord-spacing in the strip or ply are two important requirements of such ply production, the edges of the ply being most sensitive to variation. Fluctuations occuring in extruding pressure and/or in rubber viscosity may lead to poor flow in the rubber.

PRIOR ART

The extrusion of material through a progressively narrowing orifice is shown by Chuy in U.S. Pat. No. 3,994,654; also pressing, or forcing, extrudable material around or onto a strand or filament by means of a narrowing die-passage, is shown, for example by Cook in U.S. Pat. No. 2,401,551, and by Kertscher in U.S. Pat. No. 4,165,957, both of whom employ a compression cone whose diameter narrows progressively; in U.S. Pat. No. 4,050,867, Ferrentino et al similarly disclose a progressively narrowing die, whose wall contour decreases from a conical portion to a parallel portion.

However, none of the above devices recognize the need, nor disclose or suggest a means, for improving the uniformity of cord-spacing and elastomer-flow in a composite strip.

It has been suggested to improve uniformity and accuracy at the ply edge by guiding the rubber laterally inwardly into a side-flow, to `pack` the edges of the ply as the cords leave the wire-guide. This, however, tends to cause stock turbulence and attendant cord-deflection.

In addition to the ply edge situation, the problem exists of providing a die system which will produce a rubberized strip in which the cord spacing is very close; i.e., how to manufacture a wire-guide having closely spaced holes sufficiently large to allow the wires to pass, while maintaining sufficient metal wall thickness between the holes. One solution advanced has been to drill alternate wire-guide holes in two rows, each angling toward the same exit plane. In this manner, wall thickness between adjacent wire holes would be increased. It has been found, however, that this results in pairing, a condition in which the cords are caused to arrange themselves into pairs, with alternating narrow and wide spacings across the rubberized ply.

Consistency in strip width and, cord-spacing are important, and were not obtainable by the above approaches.

It is thus an object of the invention to provide die-apparatus for producing a strip or ply of rubberized cords, wherein improved close cord spacing uniformity is maintained, with reduced tendency for strip-width variation due to fluctuations in extruder head pressure or rubber consistency.

SUMMARY OF THE INVENTION

The present invention comprises a die-structure providing a pre-channeled rubber-flow into an aperture whose sidewalls converge toward the die-exit, while its height increases, to present a substantially constant cross-sectional area throughout; and a cord-guide whose hole-spacing at the die entry is greater than the cord-spacing required in the ply at the die-exit.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view, partially exploded and in phantom, showing a portion of a prior art die-structure;

FIG. 2 is a top view of the die-structure of FIG. 1, in use;

FIG. 3 is a perspective view, partially exploded, showing a portion of the die-structure of the invention;

FIG. 4 is a top view of the die structure of FIG. 3, in use;

FIG. 3 is a longitudinal cross-sectional view of the assembled die-structure of FIG. 4, with the guide disposed in a housing of the extrusion nozzle.

DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 and FIG. 2 show respectively, a prior art die-structure, exploded, and its operation. In FIG. 1, a die-structure is generally indicated at 1, and comprises a die-throat 2 made up of two opposed, matching halves 3 fastened together; and a wire-cord guide insert 4. The portions 3 of the die-throat 2 and insert 4 are associated as shown in FIG. 2, and similarly to that seen in the cross-section in FIG. 5.

Parallel wires 5, only two of which are shown for clarity in FIG. 2, are advanced by means not shown in the direction of arrows 6 through openings 7 in the insert 4 and thereafter into and through the aperture of the die-throat 2, where the receive rubberization from an extruder, well known and not shown. For the sake of simplicity, and opposing halves of the die-throat being similar construction, the ensuing description will proceed on the basis of one die throat half 3. The parallel wires 5 leave insert 4, and enter the die-throat entry 8; simultaneously, rubber 9 from the extruder enters through the full-width channel formed between the insert 4 and the ramp 10, and is forced around and between the wires 5. As the rubber flows up the ramp 10 and into the entry 8 together with the wires 5, the converging walls 11 of the entry 8 of the aperture 12 within which the composite strip 13 is formed induces a significant side-flow 14 in the rubber. Such side-flow, with its substantial transverse component, tends to cause deflection of the wires 5 as shown at 15, as well as turbulence in the stock resulting in poor strip edges at 16.

Beyond the converging walls 11, the aperture 12 exhibits walls 17 parallel to each other and generally parallel to the wires 5. The entire aperture 12, from entry 8 to exit 18, has a substantially constant vertical dimension, being twice the height of walls 11 and 17.

As the strip exits, trimming means 20, such as knives or wires sever the trim 21 from the strip sides, leaving a final edge 22. But the results of the induced tapering flow 14 remain, resulting in an inacceptable product.

Turning now to FIGS. 3, 4 and 5, the die-structure of the invention comprises a cord-guide 4; and a die-throat of which only the lower half 40 is shown. According to invention, an aperture 41 for forming the composite rubber-cord strip 42 is bounded by opposing sidewalls 43 and opposing upper and lower walls 44, respectively.

The opposing sidewalls 43 converge longitudinally of the aperture 41 from a width 45 at the entry 46 to a width 47 at the exit 48. Simultaneously, the opposing upper and lower walls 44 diverge longitudinally of the aperture 41 from a height 49 at the entry 46 to a height 50 at the exit 48.

In this manner, while the cross-section of the aperture 41 at any point between entry and exit is a generally rectangular parallelogram whose major dimension remains in the same plane, the converging width, concurrent with the diverging height, of the aperture is selected such that the cross-sectional area of the aperture 41 remains substantially constant throughout, from entry to exit.

Ahead of the entry 46, the die-throat 40 is provided with laterally spaced ramp-portions 51, which are separated by a recess 52. The sidewalls 53 of the recess lead to the entry 46 and the lateral spacing between them equals the width of the entry. The ramps 51 are adapted to engage the lateral end portions of the insert 4. With the insert in place on the ramps 51, there is thus formed a pre-shaping channel 54 which constitutes the single avenue for extrusion rubber 55 to flow to the entry 46 to be joined with cords 56. Thus, in advance of its arrival in the entry 46 the rubber flow is channeled by the parallel walls 53 of channel 54 into a flow generally parallel to the direction 57 of the advancing cords 56.

From FIG. 4 it will be seen most clearly that, with the present invention, it is possible now to space the wire-holes 7 in the guide 4 an amount sufficient to allow adequate metal-wall gauge, to bring rubber along a parallel path and into engagement with the cords 56, and thereafter to narrow the entire composite strip while increasing its gauge toward the exit, thus actually drawing down the composite to the specified width. The usual trimming devices 58 sever a trim 59, leaving a finished edge 60.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2401551 *Feb 18, 1944Jun 4, 1946Auburn Button Works IncApparatus for applying plastic coatings to flexible strips and the like
US2453312 *Sep 7, 1946Nov 9, 1948Nat Standard CoExtrusion apparatus
US2468585 *Feb 8, 1946Apr 26, 1949Saint GobainProcess for producing pellicles
US3070841 *Dec 7, 1960Jan 1, 1963Goodrich Co B FMethod and apparatus for making magnetically anisotropic elongated magnets
US3280427 *Feb 3, 1964Oct 25, 1966Cooper Tire & Rubber CoApparatus for extruding composite black and white rubber strips for white sidewall tires
US3487505 *Aug 21, 1967Jan 6, 1970Dow Chemical CoLaminates
US3616496 *Jul 28, 1969Nov 2, 1971PirelliApparatus for producing a band of uncured elastomeric material embedding a plurality of reinforcing wires
US3874837 *Sep 18, 1972Apr 1, 1975Airco IncDie for extrusion of fine grained green carbon
US3994654 *Jan 2, 1975Nov 30, 1976Monsanto CompanyDie for extruding thermoplastic sheets
US4050867 *Dec 18, 1975Sep 27, 1977Industrie Pirelli Societa Per AzioniExtrusion head for extruding plastomeric or elastomeric material on filaments
US4165957 *Jun 29, 1977Aug 28, 1979Maillefer S.A.Apparatus for manufacturing electric wire having wire-enamel-type insulation
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4563140 *Nov 14, 1983Jan 7, 1986Armstrong Rubber CompanyApparatus for coating aligned cords
US4588538 *Mar 15, 1984May 13, 1986Celanese CorporationProcess for preparing tapes from thermoplastic polymers and carbon fibers
US5259746 *Feb 6, 1992Nov 9, 1993Bridgestone/Firestone, Inc.Extrusion head
US5273595 *Dec 9, 1992Dec 28, 1993Reynolds Consumer Products, Inc.Apparatus using removable profile wedges for manufacture of reclosable bag
US7056110 *Oct 8, 2001Jun 6, 2006Bridgestone/Firestone North American Tire, LlcApparatus for making reinforcement ply material
US9334607Mar 7, 2012May 10, 2016Thermoplast Composite GmbhMethod and device for producing a composite fiber material in the form of a fiber strip impregnated with a polymer
US20030096095 *Oct 8, 2001May 22, 2003Abdallah David G.Reinforced ply material with untwisted sets of steel monofilaments
US20060113026 *Jan 20, 2006Jun 1, 2006Bridgestone CorporationApparatus for coating belt cord with rubber
DE102011005462B3 *Mar 11, 2011Jun 14, 2012Thermoplast Composite GmbhVerfahren sowie Vorrichtung zur Herstellung eines Faserverbundwerkstoffes in Form eines mit einem Polymer imprägnierten Faserbandes
DE102011005462B8 *Mar 11, 2011Oct 11, 2012Thermoplast Composite GmbhVerfahren sowie Vorrichtung zur Herstellung eines Faserverbundwerkstoffes in Form eines mit einem Polymer imprägnierten Faserbandes
DE102011090143A1Dec 29, 2011Jul 4, 2013Thermoplast Composite GmbhVerfahren sowie Vorrichtung zur Herstellung eines Faserverbundwerkstoffes in Form mindestens eines mit einem Polymer imprägnierten Breit-Faserbandes
EP1213121A1 *Oct 10, 2001Jun 12, 2002Bridgestone CorporationProcess and apparatus for coating belt cord with rubber
WO1985002145A1 *Oct 22, 1984May 23, 1985Armstrong Rubber CompanyApparatus for coating aligned cords
WO2001003908A1 *Jul 11, 2000Jan 18, 2001Sachsenring Automobiltechnik AgDevice for producing a flat component, reinforced with roving
WO2010052186A1 *Nov 2, 2009May 14, 2010Societe De Technologie MichelinDual profile extrusion die
WO2012123302A1Mar 7, 2012Sep 20, 2012Thermoplast Composite GmbhMethod and device for producing a composite fibre material in the form of a fibre strip impregnated with a polymer
WO2013098224A1Dec 21, 2012Jul 4, 2013Thermoplast Composite GmbhMethod and device for producing a fibre composite material in the form of at least one wide fibre strip impregnated with a polymer
Classifications
U.S. Classification425/114, 425/461, 425/131.1, 264/171.24, 425/133.5, 264/171.21, 425/467
International ClassificationB29K21/00, B29C47/02, B21C25/02, B29C55/00, B29C47/00, B29L31/00, B29B15/08, B29C70/20, B29C47/14, B29C65/78, B29C70/06, C08J5/04, B29C65/70, B29B7/00
Cooperative ClassificationB29C47/0014, B29D2030/381, B29C47/027, B29K2021/00, B29C47/14
European ClassificationB29C47/02D, B29C47/14
Legal Events
DateCodeEventDescription
Dec 4, 1989ASAssignment
Owner name: BRIDGESTONE/FIRESTONE, INC., A CORP. OF OH.
Free format text: CHANGE OF NAME;ASSIGNOR:FIRESTONE TIRE & RUBBER COMPANY, THE, A CORP. OF OH.;REEL/FRAME:005237/0003
Effective date: 19890731
Jan 25, 1999ASAssignment
Owner name: BRIDGESTONE/FIRESTONE RESEARCH, INC., OHIO
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BRIDGESTONE/FIRESTONE, INC.;REEL/FRAME:009719/0442
Effective date: 19980601